Defensible Space: What and Why

Defensible space is the NUMBER ONE safeguard of your home against wildfire. Think of defensible space as the barrier between your home and vegetation that could directly lead to its ignition. It is important to consider not only the native vegetation that surrounds your home, but also the grass, bushes, trees, and shrubbery. 100 feet of defensible space is recommended directly around your home. This 100 feet is divided into two zones. The spacing between grass, shrubs, and trees is also crucial to reduce the spread of wildfires. The spacing needed is determined by the type and size of brush and trees, as well as the slope of the land. For example, a property on a steep slope with larger vegetation requires greater spacing between trees and shrubs than a level property that has small, sparse vegetation. The graphics and information below show specifications to create defensible space around your home. If your home needs protection and assistance from firefighters, they will be thankful you have the proper defensible space measures in place.

Zone 2

100 feet from home, buildings, structures, decks

• Cut or mow annual grass down to a maximum height of 4 inches

• Create horizontal space between shrubs and trees

• Create vertical space between grass, shrubs and trees

• Remove fallen leaves, needles, twigs, bark, cones, and small branches (permitted to a depth of 3 inches)

Zone 1

30 feet from home, buildings, structures, decks (50 feet for SD county)

• Remove all dead plants, grass and weeds, or vegetation

• Remove dead or dry leaves and pine needles from your yard, roof and rain gutters

• Remove branches that hang over your roof and keep dead branches 10 feet away from your chimney

• Trim trees regularly to keep branches a minimum of 10 feet from other trees

• Relocate wood piles to Zone 2

• Remove or prune flammable plants and shrubs near windows

• Remove vegetation and items that could catch fire from around and under decks

• Create a separation between trees, shrubs and items that could catch fire, such as patio furniture, wood piles, swing sets, etc.

Horizontal spacing depends on the slope of the land and the height of the shrubs or trees. Check the chart above to determine spacing distance.

Allow extra vertical space between shrubs and trees. Lack of vertical space can allow a fire to move from the ground to the brush to the treetops like a ladder. To determine the proper vertical spacing between shrubs and the lowest branches of trees, use the formula below. Remove all tree branches at least 6 feet from the ground.

Example: A five foot shrub is growing near a tree. 3×5 = 15 feet of clearance needed between the top of the shrub and the lowest tree branch.

(Cal Fire, 2019)